1. Field of the Invention
The field of the invention generally relates to guidewires, and specifically to a guidewire with the unique objects of piercing vascular walls, steering an extravascular pathway through surrounding tissue, anchoring at a site on the pathway created, distending the pathway, and showing the image of the guidewire and the vessel even when they overlap on the same fluro-unit screen.
2. Prior Art
Prior Art References:
YearNamePatent Number  243,396June 1881Pfarre  419,926January 1890Chapman  554,614February 1896Beyer  623,022April 1899Johnson  707,775August 1902Harris2,118,631May 1938Wappler2,211,976August 1940Hendrickson3,174,851March 1965Buehler3,416,531December 1968Edwards3,547,103December 1970Cook600/5854,003,369January 1977Heilman et al.500/5854,516,972May 1985Samson604/2824,569,347February 1986Frisbie4,676,249June 1987Arenas et al.600/5854,719,924January 1988Crittenden et al.4,886,067December 1989Palermo5,040,543August 1991Badera et al.5,059,183October 1991Semrad600/5855,060,660October 1991Gambale et al.600/5855,329,923July 1994Lundquist5,381,782January 1995DeLaRama et al.5,477,856December 1995Lundquist5,599,326February 1997Carter604/2825,664,580September 1987Erickson et al.600/5855,685,868November 1997Lundquist604/2805,741,429April 1998Donadio, III et al216/85,762,615June 1998Weier5,957,903September 1999Mirzaee et al.5,984,877November 1999Fleischhacker, Jr.6,056,702May 2000Lorenzo6,500,130December 2002Kinsella, et alApplicationPub. No.  0195457October 2003LaFontaine, et al  0073238April 2004Makower  0116946June 2004Goldsteen, et al  0111733May 2006Shriver606/153
Percutaneous Catheter-Based Interventions
Atherosclerotic disease of the coronary, carotid and peripheral arteries accounts for more deaths among Americans than all other disease processes combined. Despite effective preventive care in the form of lifestyle, interventions, aspirin, statins, beta blockers, and ACE inhibitors, primary vascular interventions are required in more than 2 million cases in the United States each year. These vascular interventions are either surgical placements of bypass grafts around atherosclerotic occlusions or percutaneously introduced catheter-based devices for going through the occlusions. In percutaneous interventions a guidewire and/or catheter is inserted in the vascular system at a readily accessible location and advanced through vessel lumens as the vessels curve and branch in different directions until the distal tip of the guidewire is proximate a desired target site. These guidewires are specifically designed to stay within the vessels (intravascular) and not injure the vessel walls. The guidewire may be advanced through stenoses or partial occlusions in the vessel lumen such as plaque. This is done with a blunt end to avoid injury to the vessel walls. After the guidewire crosses a stenosis in this manner, an interventional device such as a catheter, balloon and stent is typically advanced over the guidewire to open the blockage and keep it propped open. Thus the guidewire establishes the intravascular pathway for the interventional catheter that follows. These catheter-based vascular interventions increase blood flow through blockages in coronary and peripheral arteries. In addition to these catheter-based interventions there are procedures for placing bypass grafts around the occlusions in coronary and peripheral arteries to increase blood flow. The only procedure for placing bypass grafts in use today is surgical. Bypass grafts last longer than catheter-based percutaneous procedures but the surgery is far more traumatic than percutaneous intervention. To make bypass grafts available without surgery several devices have been invented to place bypass grafts percutaneously by catheter-based methods rather than surgical methods. Since bypass grafts are placed outside the artery rather than inside (as balloons and stents are) the patent applications for placing bypass grafts percutaneously describe components for going outside the vasculature (extravascular) to deliver or guide the delivery of bypass grafts. Four patent applications for placing bypass graft percutaneously use the coronary arteries as application situations. And since the coronary arteries are located inside the pericardium, and the pericardium is filled with pericardial fluid, all the devices have only the object and means of moving through a transparent fluid medium. Peripheral arteries are in the lower extremities and are not surrounded by fluid but by muscle and other tissue. Thus prior art for placing coronary bypass grafts percutaneously is not emtirely applicable to peripheral arteries. About half the cases needing intervention are in peripheral arteries so the need is as great as in coronary arteries. But for bypass grafts to be placed around occlusions in peripheral arteries, a pathway must be established and distended in muscle tissue for a bypass graft—typically of several centimeters in length and about 3-8 mm in diameter. There is no prior art for a guidewire with the object of operating extravascularly in tissue nor any means for accomplishing the objects. And there are only 4 patent applications for percutaneously placing bypass graft in a transparent fluid medium found surrounding the coronary arteries. The means used in those inventions for operating in fluid will be described below and shown to be limited to transparent fluid media. In this event, it means there is no prior art to which the present invention for placing bypass grafts in peripheral arteries can be compared. But various means have been invented over more than a century to accomplish other objects with means similar to means used today. So these means will be discussed before describing the 4 patent applications that require extravascular travel through the fluid medium surrounding coronary arteries.
Objects and Means of Early Devices
The objects of the earliest devices with means recognizable as similar to those used in guidewires of today were for replacing parts in the body. There was no “guidewire” term but a “wire-wound coil” is found in early patents. In U.S. Pat. No. 243,396 by Pharre in 1881, he describes a coil of wire wound the way most guidewires are wound today, but on a mandrel of curved glass, and covered with vulcanized rubber or other material. The object of the device was to provide a curved replacement for a section of colon with the object of being more comfortable than the straight section of tubing previously available. The wire coil made a curved product possible and glass could be shaped to serve as a mandrel. Vulcanized rubber was a new material and may have been the only material in 1881 that made this invention possible. But today there are hundreds of materials that could be used—and are. In 1890 Chapman, in U.S. Pat. No. 419,926, describes a similar “catheter” device that includes covering the wire coil with celluloid rather than rubber. The early devices were not called guidewires because their object had nothing to do with guiding a catheter but were to substitute for body parts of similar shape. The objects for similar means had changed by 1938 when Wappler was issued U.S. Pat. No. 2,118,631 for changing the characteristics of a soft rubber uretheral catheter with what he called a “stylet.” The object was not to replace a body part but to change the characteristics of a catheter that was inserted in the body and then removed. Thus the object was more like objects of today's guidewire than those of half a century before but still different. The “stylet” device had an outer layer of “wire-wound spring steel wire” just as many guidewires do today. Wappler called the device a “stylet” but it had blunt ends and no sharp point that is a characteristic of a stylet in today's medical terms. It had a more rigid tube inside the wire-wound coil that is similar to hypo tubes used today. This tube housed still another stiffening agent of a solid wire attached at each blunt tip. A safety ribbon in today's guidewires is very similar to that wire. But Wappler had no need for a safety wire. His object in using this wire and the other components of his “stylet” was only to achieve certain stiffness characteristics and not used in a way that would break the spring steel coil. As Wappler claimed, his device was “ . . . to provide the requisite amount of rigidity for the primary purpose of facilitating entry of the catheter.” So despite the similarity of means the object of those means and the objects of today are quite different.
Materials Limited in Early Devices Become Plentiful
The wire used in wire coils was generally described as “spring steel” up until the 1940's when the Naval Ordinance Laboratory developed NITINOL. Today's options include NITINOL, Eligiloy and other flexible metals for a coil and polymers and carbon fiber for hypotubes and other flexible catheters that can be used as guidewires. In some of the referenced patents, slots are cut in those flexible materials to enable them to bend more readily than they do with their inherent characteristics. No purpose is served in describing each of the slot patterns. It is sufficient to say that the slots are described as being in many patterns. It may be seen that a spiral helical cut in a solid tube can produce the same guidewire that is made by coiling a wire on a mandrel. With the abundance of materials and processes available today, essentially the same characteristics can be obtained by a variety of optional materials, processes, and treatments. There may be practical reasons for choosing a particular material or process that would be optimal for the number of units to be produced, i.e. economies of scale. But even that basis of selection could easily change during a patent period as could the practical experience in manufacturing one alternative over others. It is recognized by those experienced in the state of the art that the characteristics of flexible tubes can be effected by both process and material in their manufacture and that the same characteristics with respect to the certain objects can be obtained by different materials and manufacturing processes.
A guidewire is commonly made of a plurality of turns of a wire wrapped around a mandrel and less commonly of flexible tubes or tubes with various slot patterns cut to gain the same or similar characteristics a wound wire can provide. The mandrel used for manufacture of coiled wire is removed leaving a lumen in the guidewire which can have various “core” wires inserted in it. One such wire is called a “safety ribbon” with width greater than thickness, attached at the proximal and distal ends of the wire coil by brazing, soldering, welding, laser, adhesive, etc. This ribbon serves as a means of retrieving the coil from the body in the event the coil breaks at any point while under stress such as produced while crossing an occlusion. Core wires are typically made of high tensile strength stainless steel though other materials such as NITINOL and Eligiloy are also used.
Availability and Interchangability of Materials, Processes and Shapes
It is recognized that the term “wire” should not be taken as limiting a wire to a circular cross section, material or method of manufacture. A wire of any cross-sectional shape can be extruded but typically guidewire manufacturers of today use grinding to achieve different cross-sectional shapes. The most appropriate methods in the future may include processes different than those in typical use today to obtain particular wire shapes. For instance a ribbon wire used as a safety wire in many guidewires today are likely to be made of metallic materials such as stainless steel, tantalum, titanium, or a nickel-titanium alloy known as NITINOL but may be made of non-metallic material such as a polyurethane-based polymer that has shape memory similar to that of NITINOL. Likewise, methods of connecting materials include welding, brazing, soldering, adhesives and laser-based treatments. These are obvious alternative processes for making a connection called for in an invention. One or another process or material may be selected for an advantage based on such factors as production quantities but in terms of a patent they are obvious alternatives to anyone skilled in the art.
Making Guidewires Steerable and Rotatable
Guidewires are commonly made steerable within the branching vessels they navigate. The simplest means is by imposing a “J” bend or curve on the distal end by the manufacturer or by the operator prior to its introduction into the body. However this type of guidewire must be removed from the body to impart a different curvature and so the term “steerable” generally refers to devices in which the amount of curvature can be changed without removing the guidewire from the body. A steerable guidewire must be capable of being rotated to turn the plane of the curve in the direction desired by the operator. Rotating a guidewire is usually done with the aid of a clip clamped to it at the proximal end and is called “torquing.” A wire-wound coil is not very effective in transmitting torque from the operator's proximal end to the distal end because the wire coil is likely to slightly increase in diameter to absorb the energy of rotation until it is great enough to result in rotation. This is typically described by operators as taking 180 degrees of rotation before the guidewire tip “snap rotates” 180 degrees, making all degrees between inaccessible. The inclusion of the safety ribbon attached at the proximal and distal ends of the coil provides for an increase in torque transfer between ends of the coil. The steering of the guidewire is sometimes accomplished by placing a curved wire in the guidewire lumen that causes the guidewire to approximate the same curvature and thus turn the plane of curvature in the direction the operator rotates the guidewire to move in. The stiff curved wire transfers the torque of rotation better than the wire-wound tube thus avoiding the problem of transferring rotational torque through the wire-wound coil. The object is to steer the guidewire in the lumen of one vessel into the lumen of another branch. This is typically described as a “tortuous” route between entry point and final destination when coronary arteries are the application area. The routes in peripheral arteries are much straighter and not described as “tortuous.” A characteristic of current intravascular guidewires is a soft, flexible, lubricious distal section and blunt tip suitable for avoiding injury within a vessel. A coating of polytetrafloroethelene (PTFE) or other lubricious material over the blunt tip, distal end, several sections or all of the guidewire is typically used on most guidewires today so less force is required to move within the vessel and thus avoid injury to vessel walls.
Objects and Means of Steering Guidewires
In most steerable guidewires one of two means of curving the guidewire to steer it are used. One is a curved member in a straight flexible tube that imposes a curve on the distal segment of the guidewire when advanced into the segment. Kinsella utilizes this means. It has the effect of delivering more of the force in the direction of the curve but the amount of curvature is fixed by the amount placed on the curved wire during manufacture. With an object of piercing tissue a stiff stylet wire is needed to keep the guidewire (relatively) straight, and deliver the maximum force vector in line with the straight section of the guidewire not the curved section. A straight guidewire is stiffer than a curved one and more of the force applied at the proximal end will follow the straight path forward than will follow a curved path. Therefore the better means for accomplishing the object of piercing tissue is to have the guidewire straight rather than curved when it is being advanced extravascularly through tissue or at an acute angle of 30-45 degrees toward the wall of a vessel from inside or outside the vessel. The angle preferred for placing bypass grafts is about 30 to 45 degrees with respect to the artery. To satisfy this object, the stylet wire should produce curvature in the guidewire in about this range of angles when it is fully advanced in the guidewire with piercing point extended beyond the guidewire. However it is desirable for the guidewire to be further adjusted by pulling or relaxing the ribbon wire. It should be recognized that the stylet wire imposes its maximal stiffness on the guidewire when it is at the angle with respect to the vessel wall that is favored for placing the bypass graft. Pulling the ribbon wire stiffens the guidewire somewhat more than when the ribbon wire is relaxed. Therefore an object is for the guidewire to stiffen as the ribbon wire is pulled rather than stiffen as it is relaxed. That is, the sharp stylet wire should stiffen the coil and the pull wire stiffen it still more when piercing tissue. The guidewire described by Kinsella does not have the means of operating in this way. But neither does it have the object nor means of exiting the lumen to pierce tissue. But it does have a guidewire that straightens as it is pulled. This is different from most steerable guidewires that increase their curvature as their pull wire is pulled.
Object Determines Advantage in Pulling vs. Relaxing a Pull Wire
The means of curving a guidewire by pulling a wire that causes an inherent curvature in the distal section of the guidewire to increase when pulled is different from that of Kinsella and much more common. For instance invention U.S. Pat. No 4,719,924 by Crittendenden et al, in 1988 and later a variation in U.S. Pat. No. 5,381,782 by De La Rama et al in 1995 used a pull wire to cause the distal end to curve, not to straighten. That method creates the minimal stiffness at the distal end when maximally curved and relatively small stiffness when the guidewire is relatively straight (with the pull wire relaxed). That means satisfies the object of not damaging the vessel during intravascular travel but is contrary to the object of piercing the vessel wall for extravascular travel. What is an advantage of a means with respect to one object, is a disadvantage with respect to another object. Today's guidewires have the object of intravascular travel but do not aim at extravascular travel and generally do not use the means Kinsella used for that reason. The 1970 invention by Cook used a safety ribbon wire to straighten a curved section by pulling the coiled wire guidewire apart to lengthen the guidewire and thus tighten the fixed length of the safety ribbon attached to the guidewire at the proximal and distal ends. This method of increasing tension on the pull wire was awkward and Cook did not have the objective of maximal stiffness in the straight ahead direction that his device produced. Cook's object was to avoid piercing a vessel wall just like all of today's guidewires for intravascular travel. But his means was not the best for doing that. The object of all intravascular guidewires is to avoid piercing a vessel wall and that is more easily done with a pull wire that curves the guidewire rather than a pull wire that straightens it when pulled—because a straight coil is stiffer than a curved coil. But when the guidewire is used to pierce the vessel, and travel extravascularly through tissue, it is a disadvantage to have what is an advantage for moving intravascularly.
Object of Distinguishing Overlapping Images on Fluro-Unit Screens
In certain patent applications the terms “radiodense,” “radiopaque,” and “radiolucent” are used. The terms refer to the density of the materials used in percutaneous procedures performed in a cath lab and how they appear on fluroscopic screens of fluro-units. A dense material such as platinum will show as bright, a less dense material such as steel or iodine contrast will show as dark and still less dense material such as tissue will show a faint image, if any. Almost all procedures are conducted without bright images from radiodense materials. This is because two types of images that can be distinguished when overlapping in line-of-sight are not needed in intravascular use—and since dense materials like platinum are expensive and radiopaque materials are inexpensive, radiopaque images are common. If there were objects that required distinguishing images of things in the same line-of-sight, cost would not inhibit the use of a radiodense image for one and a radiopaque image for the other. This distinguishing of images is not needed for intravascular movement but is for extravascular travel. However when the guidewire moves extravascularly, the operator must have an image of the guidewire and the vessel to keep the guidewire on a parallel pathway. When both are overlapping in the same line-of-sight they cannot be distinguished if they are both dark images. Since the operator must have a means of seeing both elements in both side and plan views on the screens in order to navigate, the images must be made distinguishable and making a linear section of the guidewire or a radiodense material produces a bright image that can be seen in the same line-of-sight as a radiopaque dark image. That is not an object in prior art so this means of accomplishing it has not been needed for intravascular guidewire travel.
Object of Dilating Guidewire Pathway
In the peripheral arteries it is necessary to provide for increasing the diameter of the pathway for a bypass graft so it will fit within the (dilated) pathway for connection on both sides of the occlusion in the artery. This dilation is not an object of intravascular interventions as guidewires used for interventions move only inside vessels. They are not used to create pathways through tissue for placing bypass grafts and not used to dilate such pathways. In the 4 patent applications for placing bypass grafts on coronary arteries dilation is not an object because fluid needs no dilation and coronary applications are strictly fluid inside the pericardium. Since there is no need for dilation in percutaneous interventions there is no object and no means in prior art for providing dilation.
Shape Memory and Anchoring
A shape is placed on a wire made of shape memory material such as the metal NITINOL or the polymer oligodial during manufacture. But it returns to the simple wire shape until activated by heat or electrical stimulus to assume the “remembered” shape. The shape may be in the form of a knot or something else larger than the wire so that it provides an “anchor” to keep the wire from being pulled through, a hole the diameter of the wire. Intravascular guidewires have no object for being anchored in a vessel. Therefore anchoring by means of memory shape materials is not used in the guidewire prior art.
Guidewire Coatings
Using a lubricious material such as PTFE to coat all or part of intravascular guidewires is common, almost universal today. This means allows the guidewire to move with the application of less force thus helping to avoid damage to vessel walls. Moving a guidewire extravascularly through the resistance of tissue would be made easier by the same means, but since such an application has never been required (a fluid medium presents no resistance) there is no prior art for this use of a lubricious material.
Arteries in a Fluid Medium or a Tissue Medium in the Body
It is evident that the pericardial fluid surrounding the coronary arteries, veins, heart and aorta offers no resistance to the probe, guidewire, catheter, curved wire or object of any other description that moves extravascularly through this fluid medium. It is just as evident that the peripheral arteries in the legs are not in a fluid medium but are in muscle tissue. Therefore the means of moving extravascularly in the pericardial fluid are not applicable to peripheral arteries. The present invention is intended to apply to peripheral arteries. This requires extravascular pathways through tissue to percutaneously place bypass grafts on peripheral arteries. Thus the guidewire must have the objects of piercing vessel walls, moving through tissue surrounding peripheral arteries, re-entering the vessel to be anchored directly at the distal site of re-entry or anchored at a still more distal site reached by intravascular movement, another exit through a vessel wall, and piercing skin to anchor outside the body, distending the initial pathway to be large enough to accommodate a bypass graft, and providing distinguishable images of vessel and guidewire on fluro-unit screens even when both are in the same line-of-sight. There is no prior art with these objectives or means disclosed for accomplishing the unique objects. Thus, as stated previously, there are no direct comparisons to prior art.
Intravascular Objects vs. Extravascular Objects
The term “extravascular” is used here to refer to movement outside the vessel—as opposed to “intravascular” movement inside a vessel. Intravascular movement is the object of guidewires today with certain exceptions for percutaneous placement of bypass grafts in coronary applications that are now discussed. The first exception is a trivial case where percutaneous entry for intervention utilizes a hypodermic needle to pierce the skin and a thin layer of tissue to enter the vascular lumen. U.S. Pat. No. 3,547,103 by Cook in 1970 provides a description of this method of entry after which the guidewire invented by Cook is introduced into the vessel lumen through the lumen of the hypodermic needle. Though the object of this use of the hypodermic needle is similar to the object of other prior art to be discussed, the thickness of tissue to be pierced is so small and the path to be followed so straight that a device designed for a different object (introduction of fluid in the body through the skin) is convenient, usable and not patented. If there was a patent it expired before 1896 when Beyer's U.S. Pat. No. 554,614 described a modification to a syringe.
Four Prior Art Inventions with Extravascular Objects and Various Means
There are four prior art patent applications (referenced above) where extravascular travel is an object. All four have the overall object of placing bypass grafts percutaneously. Since bypass grafts are always placed outside the occluded vessel and connected proximally and distally with respect to the occlusion, this requires the establishment of an extravascular path. However all four used the coronary arteries for the application situation, and thus all extravascular movement was through the fluid medium within the pericardium where the heart and coronary arteries are located. Though all claimed to be applicable to other parts of the body, none provided the means for extavascular travel in a medium other than liquid. These patent applications for placing bypass grafts percutaneously are by LaFontaine, et al, 0195457, 10/2003, Makower, 0073238, 4/2004, Goldsteen, et al 0116946, 5/2006, and Shriver, 0111733, 5/2006. The components of each that provide the extravascular pathway between the proximal or distal sites through fluid are summarized as follows:
Mackower's component for passing through a vessel wall, at both the proximal and distal sites for the bypass on the coronary artery, travels extravascularly to an adjacent parallel coronary vein. He describes it as a sharp-tipped or semi-rigid cannula (probe) of stainless steel, NITINOL or polymer, capable of being inserted in the tissue alone—or with a relatively rigid wire, antenna, light guide or energy guide capable of being inserted in the tissue alone or with the sheath as support. Since the distance between a coronary artery and the parallel coronary vein is only a few millimeters the extravascular distance this cannula needs to travel between proximal and distal sites is a fraction of one percent of the extravascular distance a guidewire needs to travel between proximal and distal sites in a peripheral artery application. The path is straight between a coronary artery and the parallel coronary vein so the cannula does not need to be flexible as it does in a peripheral artery application. The cannula is straight and may or may not contain a “relatively rigid wire” as it is “sharp tipped.” It should also be noted that the cannula passes through pericardial fluid, not tissue, to enter the coronary vein. Thus it is visible with or without fluro-unit screens. Because the veins are “tied off” at either end by an endovascular opening in the chest, direct visual means of viewing are available that are not available when using a guidewire extravascularly in peripheral arteries. Thus, though the object of this device includes extravascular travel, the object is not extravascular travel through tissue. Mackower does not limit his object to extravascular travel in a fluid medium—perhaps because he didn't perceive the limitation. Neither did he acknowledge the limitation of his object nor means to travel only a tiny distance though the limitation is obvious. There is virtually no similarity between this device and a guidewire for traveling extravascularly. The short rigid cannula cannot travel in a curving path for distances a hundred times greater than the length of the cannula. It is probably capable of piercing tissue but provides no way to distend tissue. Mackower has no object or means of viewing a coincident image of device and vessel on a fluro-unit screen but can depend on direct visual contact through endovascular openings. In short, though extravascular travel is an object of Mackower's invention, the objects and means of extravascular travel in the coronary artery application situation are not applicable in the peripheral artery situation.
Goldsteen, et al, use a tube or guidewire that must first cross the occlusion in a coronary artery to allow a stylet wire to emerge from the lumen through a side opening at a site just beyond the occlusion. The stylet wire is pushed through the vessel wall to extravascularly enter the interstitial space which is a fluid medium within the pericardium. It is essential that this be in a transparent fluid medium because the end of this wire is found by a fiber optic light and lens advanced through an arteriorotomy in the aorta at the proximal site. A gooseneck snare is also passed through the same proximal arteriotomy to snaring the short length of stylet wire outside the artery and drawing it back through the arteriotomy and intravascularly through the guiding catheter to the operator. This single wire is anchored by both proximal and distal ends being in the hands of the operator. This process of “fishing” for the short length of wire is done with visual light that requires a transparent fluid medium. The gooseneck loop must capture the end of a wire that has traveled extravascularly only a centimeter or so. This wire is a solid monofilament that presents a radiopaque image on a fluro-unit screen, but that image is not utilized. The object is to utilize a directly viewed visual image illuminated by visual light from fiber optics with light returning to the operator through the same fiber optics lens. This wire has no capability for being guided any more than to exit the artery wall at the distal site. The guidewire that delivers it to that site does not follow the wire extravascularly so no extravascular steering is possible. The “fishing” cannot be conducted in a tissue medium so the device has neither the means nor object of being applied in the peripheral artery situation. The Goldsteen device has received clinical trials but was apparently abandoned several years ago.
LaFontaine, et al, advanced a cutting catheter or cutting guidewire through an inverted bypass graft emerging from its connection at the proximal site on the aorta to the vicinity of its distal site on the coronary artery. The cutting tip of the guidewire/catheter is hollow like a hypodermic needle and may have a wire in the hollow lumen. It is used to go in a relatively straight path from aorta to coronary artery. The means of guiding it to the desired site is not described, but presumably by a radiopaque image on fluro-unit screens. The travel path must be essentially straight in order for the catheter to deliver sufficient force to cut through the artery. The distal end of this hollow needle catheter is surrounded by a collar with a beveled edge that enlarges the opening in the artery at the distal site to enable the bypass graft to enter the distal site. The bypass graft is turned inside-out to advance it through pericardial fluid to the distal site. A straight path through a fluid medium is required for this. A path through tissue would result in filling the guidewire/catheter with tissue. The path for a peripheral artery application is not straight but requires a 30-45 degree turn out of the proximal site in the artery and a 30-45 degree turn back in the artery at the distal site as well as a non-straight intravascular path. There is no object and no means of distending tissue with this device. There are no means of producing images of guidewire and vessel that are distinguishable on a fluro-unit screen as needed to keep the path from going off in random directions on a peripheral artery application. There is no object or means of providing an anchor as the bypass graft apparently is intended to enter the coronary artery as the cutting catheter makes the opening. It may be doubted that this can be accomplished even in the coronary artery application situation and there are no known tests with prototypes of the La Fontaine device as there are with the Mackower and Goldsteen devices. Thus the objects and means of the La Fontaine device may or may not be safe and effective in the coronary artery application but they clearly do not provide objects or means of accomplishing the objects required in peripheral artery applications.
Shriver uses a stylet wire with a screw tip and curve imposed by the physician to pass through an arteriotomy at the proximal site in the aorta through pericardial fluid to the coronary artery where it is twisted to anchor the screw at that site. The bypass graft is delivered in a catheter over this wire. This stylet wire is sharp enough to pass through tissue but it does not have the means or object of making multiple turns as required in turning out of the peripheral artery and turning again to re-enter it. It does not have the object or means of being steered without removing it from the body, for distending tissue, or for presenting a distinguishable image of wire and vessel as required in a peripheral artery application. Shriver, as did the others who used coronary arteries as application situations, said nothing about objects that limited the devices to coronary applications. On the contrary, all claimed generality to many other body areas. Shriver (and others) may have overstated the generality because of not adequately recognizing the difference with respect to other applications such as peripheral arteries. Now, in making an application to peripheral arteries it is clear what additional objects must be met by additional means that were not required in the fluid medium and in other specifics of the coronary application.
No Infringement on Prior Art by Same Inventor or others
It should be recognized that the present invention does not infringe on the prior art devices for placing bypass grafts, including the previous invention by Shriver, or on prior art such as stents, both of which may be used with the present invention. The guidewire of the present invention is separate, distinct and different from the guidewire disclosed in the prior patent application by the same inventor as well as different from all other prior art. It should be recognized that the present guidewire invention could be used with the non-guidewire components of any of the prior art devices under suitable licensing agreements. There are many cases of one invention being used with another. In the case of stents, the company owning the rights to stents needed a delivery system consisting of balloons, guidewires and catheters. They simply bought the company that owned the delivery system needed for stents.
3. Objects and Advantages
Accordingly, there is no prior art with the object or means of entering the body percutaneously, piercing tissue to create an extravascular pathway, anchoring the guidewire, presenting distinguishable fluoroscopic images of guidewire and artery, steering guidewire with one hand, and dilating that pathway to the size needed to place bypass grafts around occlusions in peripheral arteries thus providing the following unique advantages of the invention;
1. To provide a guidewire that will enter the vasculature of the body percutaneously, pierce vessel walls, pierce an extravascular pathway through tissue surrounding the vessels, pierce the vessel to move intravascularly and repeat these actions as the operator desires, including piercing the skin to leave the body at a remote distal site, and also to pierce occlusions, such as plaque, if desired.
2. To provide a guidewire that is steered both intravascularly and extravascularly by an operator outside the body.
3. A guidewire assembly for piercing tissue that delivers the maximum percentage of force applied at the proximal end to the piercing element on the distal particularly when creating a curved pathway through tissue. When the guidewire is creating a straight pathway through tissue, the maximum is easily obtained. When the path must be curved the percentage is reduced. The advantage of the present invention is to utilize a section of guidewire that is curved during manufacture and straightened as needed while being steered to create a pathway in the body. This delivers a higher percentage of the force than a straight guidewire that is manufactured straight and curved while being steered to create a pathway. Backpressure from the piercing element tends to make the curve more curved and thus losing a greater percentage of the force applied to the proximal end.
4. To provide a stylet wire and ribbon wire of width greater than thickness with thickness at right angles to the plane of curvature of the flexible tube as the means of resisting lateral movement outside the plane of curvature and thus maximizing the force vector in the direction the stylet wire point and/or guidewire assembly is directed. Any lateral movement causes backpressure from the piercing element to be directed in a vectorlateral to the force applied at the proximal end.
5. To provide the means of gaining an additional force vector in the direction desired by the operator through a chisel point stylet wire that moves in the direction opposite that of the force of tissues pushing against the face of the chisel point.
6. To provide a combination of means of delivering rotational torque in smooth increments from proximal to distal end of a flexible tube guidewire, without the snap rotation typical of wire-wound guidewires, so the guidewire will point in the precise direction the operator desires the plane of curvature to be directed in and thus move the guidewire in that desired direction when advanced. The means are an stylet wire that engages a hollow tip attached to the distal end of the flexible tube and thus delivering rotational torque from proximal to distal end, and by the ribbon wire that is attached at the distal end and passing slidably through a hanger fixed at the proximal end.
7. To provide increasingly large flexible tubes for advancing over the guidewire assembly as the means to dilate the pathway created by the guidewire assembly to the desired size.
8. To provide a replacement wire for the stylet wire and/or guidewire that will anchor the guidewire inside a vessel or outside the body.
9. To provide a means of distinguishing a dark radiopaque vessel from the bright radiodense guidewire on a fluro-unit screen even when the two images are overlapping or coincident in line-of-sight.
10. To provide a mechanism that provides a means for the operator to control the components of the guidewire assembly with one hand and deliver radiopaque contrast fluid into the flexible tube and thus the vessel.
11. To provide a ribbon wire that has a secondary function of recovering the guidewire if a coil breaks.
12. To provide a means of piercing occlusions such a plaque within vessels